var Animal = function() {

	alert("this is Animal constructor");

	this.name = 'animal';

	this.age = 7;

};

Animal.prototype.getAge = function() {

	alert(this.name + "'age is " + this.age);

};

Animal.prototype.getName = function() {

	alert("this is the animal Name!");

};

var Cat = Ext.extend(Animal, {

			name : 'cat',

			age : 5,

			constructor : function() {

				alert("this is Cat constructor");

				this.superclass().constructor(arguments);

			},

			getAge : function() {

				alert(this.name + "'age is " + this.age);

				this.superclass().getAge();

			}

		});

var homeCat = function() {

	alert("this is homeCat constructor");

	this.superclass().constructor(arguments);

};

Ext.extend(homeCat, Cat, {

			name : 'homeCat',

			age : 3,

			getAge : function() {

				this.superclass().getAge();

			}

		});

var myCat = new homeCat();

myCat.getAge();
